Salamander Population and Adaptation Research Collaboration Network

Sampling salamanders in the field.

A research plot after snowfall.

Experimental snowfall removal.

The Salamander Population and Adaptation Research Collaboration Network (aka 'SPARCnet') is a group of almost 50 collaborators with the two-fold goal of (1) advancing our understanding of environmental change on salamander ecology and evolution, and (2) developing meaningful curricula that engages students and has them participate in real research. Each collaborator uses the same methods to investigate salamander responses to changes in temperature, precipitation, and other habitat features across the entire range of the focal species, the Red-backed Salamander, Plethodon cinereus. This species is among the most abundant vertebrate species in temperate forest ecosystems, despite being no larger than your finger. The scientific goals are specifically to:

1. Understand impacts of land use and climate change on salamander population dynamics.

2. Develop models to describe local and regional drivers of population dynamics.

The goal of my dissertation was to understand the historical and contemporary processes that create and maintain the disjunct distribution Hyla andersonii. This species is restricted to three isolated (disjunct) regions in the eastern United States: New Jersey, North and South Carolina, and the Florida panhandle and southern Alabama. It is considered threatened by all of the states in which it occurs. Results suggest a strikingly concordant pattern of differentiation in which the first axis of variation for acoustic signal, morphometric, and genetic data distinguishes populations along a latitudinal/longitudinal gradient and the second axis distinguishes the set of populations occurring in the Carolinas from those occurring in the New Jersey and Florida/Alabama regions. I also investigated genetic differences among populations within regions, quantified habitat characteristics among regions, and tested models of evolutionary history using high-throughput, next-generation sequence data.

Behavioral isolation and divergence of Hyla andersonii and H. cinerea in Florida

Behavioral isolation is a major barrier to hybridization among sympatric species. In anuran mating systems, the principal isolating mechanisms are acoustic signals (used in species recognition) and preferential breeding habitat. The treefrogs Hyla andersonii and H. cinerea are known to be behaviorally isolated, having different preferential breeding habitats (allotopic), although their acoustic signals are very similar. In regions of the Florida panhandle and southern Alabama, however, males of both species call for mates from the same locality (syntopic), resulting in hybrid individuals with intermediate calls and physical characteristics. We collected calls from syntopic and allotopic localities for both species in order to measure changes in acoustic signal.

The country of Colombia in South America is the most diverse in the world in number of amphibian species per unit area. One group, the Gladiator frogs, inhabit a large range of environmental conditions and exhibit fascinating behaviors that include nest-building, calling for females, and male-male combat using a bony spine on their thumb. In this study, we investigate the evolutionary and ecological factors that may have contributed to the distributions of three closely-related, species: Hypsiboas crepitans, H. pugnax, and H. rosenbergi.